Attaching devices



March 3, 1964 w. WELSH 3,123,187

ATTACHING DEVICES Original Filed July 19; 1957 2 Sheets-Sheet 1 IN VENTOR.

March 3, 1964 H. w. WELSH 3, 3,187

ATTACHING DEVICES Original Filed July 19, 1957 2 Sheets-Sheet 2 mun Swim! INVENTOR.

United States Patent Ofiice 3,l3,i87 Patented Mar. 3, 1964 3,123,187 A'ITACIHNG DEVICES Harvey W. Welsh, Indianapolis, Ind, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application July 19, 1957, Ser. No. 673,055, now Patent No. 2,963,27L Divided and this application Feb. 19, 1960, Ser. No. 9,995

3 Claims. (Cl. 189-36) This application is a division of my application Serial No. 673,055 for Rotor Blade Shrouding, filed July 19, 1957 (Patent No. 2,963,272). The present invention relates to attaching means having various uses, but disclosed herein in its preferred embodiments in shrouded blade structures for the rotors of fluid dynamic machines such as axial-flow compressors and turbines.

My invention is directed primarily to the provision of a simple, lightweight, reliable, and readily applied attachment for a part such as a rotor shroud which makes it practicable to remove the shroud, or other part, for replacement of damaged blades, for example.

:T he nature of the invention and the advantages thereof will be apparent to those skilled in the art from the succeeding detailed description of two preferred embodiments of the invention and the accompanying drawings thereof.

FIGURE 1 is a fragmentary sectional view of the rotor of an axial-flow compressor taken on a plane containing the axis of the rotor.

FIGURE 2 is a fragmentary transverse sectional view of the same taken on the plane indicated by the line 2-2 in FIGURE 1.

FIGURE 3 is a fragmentary view of the exterior of a rotor stage during assembly.

FIGURE 3a is a similar view after assembly.

FIGURE 4 is a sectional view taken on the plane indicated by the line 4-4 in FIGURE 30.

FIGURE 4a is a sectional view taken on the plane indicated by the line la-4a in FIGURE 3.

FIGURE 5 is a fragmentary axonometric exploded view of the shroud.

FIGURE 6 is a fragmentary sectional view of a second embodiment of the invention taken in a plane containing the axis of the compressor.

FIGURE 7 is an external view of a portion of the shroud of FIGURE 6.

FIGURE 8 is a greatly enlarged detail of a portion of FIGURE 7.

FIGURE 9 is a fragmentary axonometric exploded view of the shroud of FIGURES 6 to 8.

Referring to FIGURES 1 and 2, the rotor in may be of any suitable structure, but is illustrated as a composite rotor including a disk 11 and spacer rings 12 and 13 fixed to the disk by a ring of bolts 14-. The spacer rings may be similarly fixed to similar disks to provide a multistage rotor which may include a central shaft or tiebolt 16. The rim 17 of the wheel is provided with slots to receive the dovetail roots 18 of compressor rotor blades 19'. The blades may include platforms 21 adjacent the roots of the blades.

The blades extend radially outward from the disk and terminate at the blade tips 22. The blade tips are dis posed in a ring. A blade shroud or rotor shroud 24 made up of a number of arcuate segments 26 extends around the tips of the blades. The number of segments ay be varied, but a suitable number of segments is six. The shroud segments are disposed end-to-end with the ends overlapping to provide the equivalent of a continuous shroud.

The shroud 24 of FIGURES 1 to 5 is of channel section with a web 27 and outwardly extending flanges 28. At one end of each shroud segment, a tongue 29 extends from the web 27 and is slightly offset radially so as to overlie the web 27 of the adjacent section. Rectangular openings 31 are punched in the web 27 and one such opening is punched in the tongue 29. These openings are disposed at such an angle to the axis of the compressor as to accord generally with the angle of the tip of the blade with respect to the compressor axis. The tip of each blade is machined to provide a neck 32 and a head 33, the neck and head together constituting a headed tang 34 at the end of the blade. The blade shroud is dropped over the headed tang 34 of each blade with the tang extending through the opening 31.

The shroud is retained on the blade by a locking clip 36 which may readily be attached and removed and which holds the shroud seated against the shoulders 37 at the base of the tang. FIGURES 3, 3a, 4, and 4a illustrate two stages in the mounting of the locking clip. The locking clip in FIGURES 3 and 4a has been dropped over the blade tang and the clip in FIGURES 3a and 4 has been rotated so as toengage between the head 33 of the tang and the shroud in a bayonet lock and has been locked against displacement. Each clip 36 is a formed sheet metal part including a base 37 and an outwardly extending flange 3%. An opening 39 of irregular contour is cut in the base 37 of the clip. The greatest dimension of the opening is such that the clip may be dropped over the tang 34 of the blade. Portions 41 of the base of the clip at each end are deformed upwardly and are disposed so that upon rotation of the clip to the position shown in FIG- URES 3a and 4, the portions 11 engage under the shoulders 33 of the tang, as illustrated in FIGURE 1. When the clip has been rotated into this position, it is locked against disengagement by bending down two tabs 42 extending upwardly from the base 37 so that the tabs will engage the neck 32 of the blade tang and prevent the clip from rotating into the position which frees the shroud. The deformed portions 41 will yield slightly and thus provide a slight tolerance in the fit. They are too stiff to yield under centrifugal force.

As will be apparent, the shroud is easily attached and removed. After the blades have been mounted in the disk, the segments of the shroud are put over the ends of the blades. The clips are put over the ends of the blades and rotated to fit under the tangs and are locked in place by bending down the tabs 42. If it is desired to remove blades for any reason, any or all segments of the shroud may easily be removed by bending up the tabs 42, rotating the clips, and lifting them off to free the shroud for removal.

The second form of shroud structure, illustrated in FIG- URES 6 to 9, is similar in general to that previously described in that it involves a sheet metal shroud with overlapping segments fixed to the blades by locking clips. The differences are in the structure of the shroud, the provision of two tangs on each blade, and the use of a diiferent locking clip. Considering first the structure of the shroud 51, this comprises a flat arcuate strip 52 and an outer strip 53 which may be described as being of W- shaped cross-section. This strip has flanges at the edge like segments 26 shown in FIGURE 5, but also has a raised portion 54- at the center so that there are a total of four radial webs in the strip 53. The strips 53 abut the strips 5-2 and are brazed or spotwelded to them to provide a strong, stiff and lightweight shroud segment. Each blade 56 may be mounted in the same manner as shown for blades 19 in FIGURE 1, and the shroud 51 extends around the blade as does shroud 24 as shown in FIGURE 2. Each blade 56, however, has two tangs 57, each including a head 58 and a neck 59. The blade defines a shoulder 60 between the tangs and adjacent the leading and trailing edges against which the strip 52 bears. The strip 53 terminates short of one end of strip 52 and extends beyond the other end, as shown in FIGURE 9, so that the end portion 61 of strip 52 may underlie the end portion 62 of strip 53. Two rows of holes 63 and 64 are punched through the strips 52 and 53 to receive the tangs 57. At the joint between the shroud segments, the tangs go through the strip 52 of one shroud and the strip 53 of the other.

After the shrouds have been fitted over the tips of the blades, they are retained by locking clips 66, two for each blade. The clips 66 are cup-shaped, with a base 67 and a flange An elongated opening 69 is punched in the base of the clip of such dimensions as to pass over the head 58 of the tang. Upon rotating the clip 90 degrees, the base of the clip engages under the head of the tang to provide a bayonet lock joint. Two small deformable tabs "ill brazed to the flange of the clip and standing upwardly from the flange before the clip is installed may then be bent down into the position shown in FIGURE 8 where they lie at each side of the head 58 and prevent the clip from rotating so as to release the shroud.

As will be seen, the advantages of this form of the invention are similar to those of the form previously described.

The invention is not to be considered as restricted by the detailed description of the preferred embodiments thereof presented for the purpose of explaining the principles of the invention, as many modifications may be made by the exercise of skill in the art within the scope of the invention.

I claim:

1. An assembly comprising a first member having a shoulder adjacent an end thereof, a tang on the member extending from the shoulder, and an elongated generally rectangular head on the tang; a second member abutting the shoulder and having an opening for the tang eonfigured for insertion of the head therethrough, the tang extending through the opening; and a locking clip having a base with an elongated generally rectangular bayonet slot hole dimensioned for assembly over the head and rotation about the tang and to provide a bayonet lock joint between the clip and the head upon rotation of the clip, portions of the base of the clip abreast the longer sides of the bayonet slot hole being disposed between the head and the second member upon such rotation, the locking clip including a circumferential flange extending transversely to the plane of the base and away from the said shoulder generally encircling the head, and a plurality of deformable tab means on the clip deformable so as to extend from the clip generally parallel to the base of the clip into engagement with opposite longer sides of the head to lock the clip against rotation relative to the first member.

2. An assembly as recited in claim 1 in which the tab means extend from the base of the clip at the edge of the bayonet slot hole into the hole at opposite sides and near opposite ends of the hole.

3. An assembly as recited in claim 1 in which the tab means extend from the edge of the flange remote from the base in position to engage opposite sides of the head at the same end of the head.

References (liter! in the file of this patent UNITED STATES PATENTS 590,325 Leslie Sept. 21, 1897 1,720,754 Baumann July '16, 1929 2,379,296 Harbert June 26, 1945 2,673,889 Metz Mar. 30, 1954 2,812,159 Krebs Nov. 5, 1957 2,945,673 Hockert et al July 19, 1960 FOREIGN PATENTS 377,101 Great Britain July 21, 1932 1,107,413 France Aug. 3, 1955 

1. AN ASSEMBLY COMPRISING A FIRST MEMBER HAVING A SHOULDER ADJACENT AN END THEREOF, A TANG ON THE MEMBER EXTENDING FROM THE SHOULDER, AND AN ELONGATED GENERALLY RECTANGULAR HEAD ON THE TANG; A SECOND MEMBER ABUTTING THE SHOULDER AND HAVING AN OPENING FOR THE TANG CONFIGURED FOR INSERTION OF THE HEAD THERETHROUGH, THE TANG EXTENDING THROUGH THE OPENING; AND A LOCKING CLIP HAVING A BASE WITH AN ELONGATED GENERALLY RECTANGULAR BAYONET SLOT HOLE DIMENSIONED FOR ASSEMBLY OVER THE HEAD AND ROTATION ABOUT THE TANG AND TO PROVIDE A BAYONET LOCK JOINT BETWEEN THE CLIP AND THE HEAD UPON ROTATION OF THE CLIP, PORTIONS OF THE BASE OF THE CLIP ABREAST THE LONGER SIDES OF THE BAYONET SLOT HOLE BEING DISPOSED BETWEEN THE HEAD AND THE SECOND MEMBER UPON SUCH ROTATION, THE LOCKING CLIP INCLUDING A CIRCUMFERENTIAL FLANGE EXTENDING TRANSVERSELY TO THE PLANE OF THE BASE AND AWAY FROM THE SAID SHOULDER GENERALLY ENCIRCLING THE HEAD, AND A PLURALITY OF DEFORMABLE TAB MEANS ON THE CLIP DEFORMABLE SO AS TO EXTEND FROM THE CLIP GENERALLY PARALLEL TO THE BASE OF THE CLIP INTO ENGAGEMENT WITH OPPOSITE LONGER SIDES OF THE HEAD TO LOCK THE CLIP AGAINST ROTATION RELATIVE TO THE FIRST MEMBER. 